Platte River Caddisfly: A Backwater Specialist
By Lindsay Vivian
The Platte River caddisfly (PRCF), Ironoquia plattensis,is an aquatic insect found in central Nebraska backwater sloughs. Formally described in 2000, the PRCF was incidentally discovered by a team of researchers studying the effects of hydroperiod on macroinvertebrate assemblages in wetlands along the Platte River. The PRCF was first noticed on land in buckets intended to capture amphibians. While most caddisflies live in water through the time they emerge as adults, the PRCF spends three months aestivating (insect hibernation) on land during the larval and pupal stages of its lifecycle. The terrestrial life stage in the PRCF is thought to be an adaptation to avoid the stress of summer dry periods that occur in prairie systems. Aestivation in the terrestrial environment has been observed in the other five species in the Ironoquia genus and in the Nothopsyche genus.
In a life history study of the species, the PRCF began aestivating before the type locality (where it was described) dried in the summer. Because the PRCF lifecycle parallels the hydroperiod of central Nebraska sloughs and the nearby Platte River, it may be considered an important indicator species of wetland health in the region. Absence of the PRCF may indicate a slough no longer retains the necessary hydrological characteristics to support a population of the species. The sloughs in which the PRCF lives are intermittent wetlands that remain wet for most of the year, but often go dry during the summer, and the PRCF has adapted to these environmental extremes.
After the discovery of the PRCF, several surveys were conducted in 1999 and 2004 and again in 2009-2010 to identify additional populations of the species. Surveys in 1999 and 2004 found PRCF populations along a 100-kilometer (60-mile) stretch of the Platte River between Gibbon, NE and Central City, NE. From recent survey work, the PRCF is now known to occur between Sutherland, NE and Havens, NE (320 km or 200 mi), and including historic sites, 26 extant PRCF populations are known. Survey information will be important in determining whether the species is in need of federal protection under the Endangered Species Act.
Important literature references for the PRCF include:
Goldowitz, B. S. and M. R. Whiles. 1999. Investigations of fish, amphibians and aquatic invertebrate species within the middle Platte River system.Final report, U.S. Environmental Protection Agency, Cooperative Agreement X99708101, Kansas City, Kansas, USA.
Goldowitz, B.S. 2004. Survey for the Platte River caddisfly (Ironoquia plattensis) in Nebraska. Final Report. Nebraska Game and Parks Commission, Lincoln, Nebraska, USA.
Whiles, M. R., B. S. Goldowitz, and R. E. Charlton. 1999. Life history and production of a semi-terrestrial limnephilid caddisfly in an intermittent Platte River wetland. Journal of the North American Benthological Society18:533-544.
Whiles, M. R. and B. S. Goldowitz. 2001. Hydrologic influences on insect emergence production from central Platte River wetlands. Ecological Applications11:1829-1842.
Whiles, M. R. and B. S. Goldowitz. 2005. Macroinvertebrate communities in central Platte River wetlands: patterns across a hydrologic gradient. Wetlands 25:462-472.
Vivian, L.A. 2010. Updates on the distribution and population status of the Platte River caddisfly, Ironoquia plattensis, and an assessment of threats to its survival. Thesis, University of Nebraska at Kearney, Kearney, Nebraska, USA.
Above. Picture of an empty PRCF larval case. Most caddisflies construct cases around the abdomen as larvae for protection from predators. Some caddisflies use sand and grain material (PRCF), while others use leaf material. This often depends on their surroundings.
Below. The PRCF can be found in backwater sloughs very similar in appearance to the one shown near Gibbon, NE.